JP5434782B2 - Magnetic measuring device - Google Patents

Description

  The present invention relates to a magnetic measuring device.

  A magnetic sensor using optical pumping is used in a biomagnetic measuring apparatus that detects a magnetic field emitted from a living heart or the like. As such a magnetic sensor, each cell in which gas is sealed is irradiated so that pump light having a circularly polarized component and probe light having a linearly polarized component are orthogonal to each other, and a magnetic field emitted from a living body is generated by the probe light. There is something to detect. Patent Document 1 below discloses such an optical pumping atomic magnetometer.

JP 2009-236599 A

By the way, when measuring a wide part of a living body by arranging a plurality of independent cells, if the gas pressure in each cell is not uniform, the measurement sensitivity of magnetism in the cell varies.
The present invention provides a technique for improving the measurement accuracy by making the pressure in a cell uniform in a magnetic measurement device that measures magnetism by arranging a plurality of cells.

A magnetic measurement device according to one embodiment of the present invention includes a cell array including a plurality of cells including therein an atomic group composed of a plurality of atoms excited by circularly polarized light,
A pump light irradiation unit that irradiates each cell with pump light having a circularly polarized light component;
A probe light irradiation unit that irradiates each cell with a probe light having a linearly polarized component so as to be orthogonal to the irradiation direction of the pump light;
A detection unit for detecting the probe light irradiated to each cell by the probe light irradiation unit,
The plurality of cells are separated from adjacent cells by walls, and holes are provided in the walls.
A cell connected to two or more adjacent cells among the cells is connected to an extension line in the moving direction of the atom entering and exiting the hole communicating with one adjacent cell and to another adjacent cell. The hole is provided so that the extension line in the moving direction of the atom entering and exiting the hole does not coincide. According to this configuration, the gas pressure in each cell becomes uniform, and the magnetic detection accuracy can be improved.

In another preferred aspect of the magnetic measurement apparatus according to the present invention, the atomic group composed of the plurality of atoms may be an alkali metal atom.

A magnetic measuring device according to the present invention. In still another preferred embodiment, a buffer gas may be contained inside the cell.

It is a block diagram which shows the structural example of the magnetic measuring device which concerns on embodiment. It is a mimetic diagram showing a magnetic sensor array concerning an embodiment. FIG. 3 is a schematic diagram of a magnetic sensor array as viewed from the direction of arrow A in FIG. 2. (A) And (b) is a figure explaining the movement of the atom in a magnetic sensor array. (A) is a figure which shows the magnetic sensor array and pump light irradiation unit which concern on embodiment. (B) is a figure which shows the magnetic sensor array which concerns on embodiment, a probe light irradiation unit, and a detection unit. It is a figure explaining the magnetic sensor array which concerns on the modification 1. FIG. (A) And (b) is a figure explaining the magnetic sensor array which concerns on the modification 2. FIG. It is a figure explaining the magnetic sensor array which concerns on the modification 3. FIG. It is a figure explaining the magnetic sensor array which concerns on the modification 4. FIG.

  The magnetic measurement apparatus according to the present invention measures a magnetic field generated from a living heart or the like. FIG. 1 is a block diagram showing a configuration of a magnetic measurement device according to an embodiment of the present invention. As shown in FIG. 1, the magnetic measurement device 1 includes a magnetic sensor array 10, a pump light irradiation unit 20, a probe light irradiation unit 30, and a detection unit 40.

  Here, the configuration of the magnetic sensor array 10 will be described with reference to FIGS. FIG. 2 is a schematic diagram showing the magnetic sensor array 10, and FIG. 3 is a schematic diagram of the magnetic sensor array 10 viewed from the direction of arrow A in FIG. As shown in FIGS. 2 and 3, the magnetic sensor array 10 according to the present embodiment includes three cells 11, 12, and 13 arranged in a line. Hereinafter, when these are not distinguished, they are simply called cells.

Each cell is made of a material such as glass that transmits light, and is a cube-shaped object that contains predetermined atoms inside. The predetermined atom in the cell is an atom that is excited by circularly polarized light and spin-polarized. For example, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and An alkali metal such as francium (Fr).
In addition to these alkali metal atoms, the cell may contain a buffer gas such as helium (He) or nitrogen (N). Predetermined atoms are contained in the cell in the state of gas (gas), and the atoms that are spin-polarized in the cell perform precession according to the magnitude of the magnetic field from the specimen. The alkali metal atoms may be in a gaseous state when detecting magnetism, and may not always be in a gaseous state.
Each cell is provided with a hole a (a11, a21, a22, a31) on a surface facing an adjacent cell. The cells 11, 12, 13 are connected by connecting the portions of the holes a with connecting pipes b (b 11, b 12) that are straight pipe lines formed of the same material as the cells. Thus, in this embodiment, the pressure of the gas in each cell is made constant by connecting the hole a provided in each cell by the connecting pipe b.

As shown in FIGS. 2 and 3, the magnetic sensor array 10 of the present embodiment has an extension line in the direction of movement of the atoms entering and exiting the connection tube b11 (broken arrow P1) and the movement of the atoms entering and exiting the connection tube b12. The extension line in the direction (broken arrow P2) is configured not to match. This is because, by providing a hole a in each cell, when an atom precessing in the cell moves to another cell at a distant position via the connecting tube b (b11, b12), This is a configuration for preventing the magnetism in the cell from being accurately measured.
For example, as shown in FIG. 4 (a), an extension line in the moving direction of the atoms entering and exiting the connecting tube b11 (broken line arrow P1) and an extending line in the moving direction of the atoms entering and leaving the connecting tube b12 (broken line arrow P2) When the connecting pipes b11 and b12 are provided so as to coincide with each other, that is, when the connecting pipe b12 is provided on the extension line in the direction in which atoms flow into the cell 12 via the connecting pipe b11, the atoms in the cell 11 A part of can move to the cell 12 through the connecting pipe b11 and can easily move to the cell 13 through the connecting pipe b12 on the extension of the moving direction.
On the other hand, as shown in FIG. 4B, in this embodiment, an extension line of the broken line arrow P1 of the atoms moving in and out of the connecting tube b11 and a broken line arrow P2 of the moving direction of the atoms moving in and out of the connecting tube b12 are used. Connection pipes b11 and b12 are provided so that the extension lines do not coincide with each other, and the cells 11, 12, and 13 are connected. That is, the connection tube b12 is provided at a position that is not on an extension line in the direction in which atoms flow into the cell 12 via the connection tube b11. Therefore, even if some atoms in the cell 11 move to the cell 12 through the connecting tube b11, the connecting tube b12 is provided at a position that does not coincide with the moving direction. Cannot easily pass through the pipe line of the connecting pipe b12.
In this way, by connecting the cells so that the extension lines in the moving direction of the atoms entering and leaving the connecting tube b11 and the connecting tube b12 do not coincide with each other, the atoms in the cell 11 can be compared with the case of FIG. Movement to a non-adjacent cell away from the cell 11 such as movement to the cell 13 or movement of an atom in the cell 13 to the cell 11 can be suppressed. As a result, in the measurement of magnetism in each cell, it is possible to make it less susceptible to the influence of atoms magnetized at positions away from the measurement target region.

  In the present embodiment, the number of cells of the magnetic sensor array 10 is an example in which three cells are arranged in a row, but the number of cells is not limited to this as long as it is plural. In addition, as shown in FIG. 2, a plurality of rows of connected cell groups may be used as a magnetic sensor array. Moreover, although the case where a cell is a cube shape is demonstrated, the shape of a cell is not restricted to this shape.

The above is the configuration of the magnetic sensor array 10 according to the present embodiment. Next, the pump light irradiation unit 20 will be described with reference to FIG. FIG. 5A is a diagram showing the magnetic sensor array 10 and the pump light irradiation unit 20 shown in FIG. The pump light irradiation unit 20 functions as pump light irradiation means for irradiating each cell of the magnetic sensor array 10 with pump light having a circularly polarized component.
As shown in FIG. 5A, the pump light irradiation unit 20 includes pump light irradiation units 21, 22, and 23 that respectively emit pump light from the lower surface direction of the cells 11, 12, and 13. Each of the pump light irradiation units 21, 22, and 23 has a light source that outputs laser light having a circularly polarized component as pump light, and irradiates the cells 11, 12, and 13 with pump light having a circularly polarized component, respectively. . When pump light irradiated from each of the pump light irradiation units 21, 22, and 23 is incident on the cells 11, 12, and 13, atoms in the cell are spin-polarized by the pump light and are affected by magnetism from the specimen. Perform precession.

Next, the probe light irradiation unit 30 and the detection unit 40 will be described with reference to FIG. FIG. 5B is a diagram illustrating the magnetic sensor array 10, the probe light irradiation unit 30, and the detection unit 40 illustrated in FIG. 2.
The probe light irradiation unit 30 functions as probe light irradiation means for irradiating each cell of the magnetic sensor array 10 with probe light having a linearly polarized component. As shown in FIG. 5 (b), the probe light irradiation unit 30 includes probe light irradiation units 31, 32, and 33. The probe light irradiation units 31, 32, and 33 each have a light source that outputs laser light having a linearly polarized component as probe light, and the probe light having the linearly polarized component is directed in the direction of the arrow with respect to the cells 11, 12, and 13. Irradiate. The polarization plane of the probe light irradiated on the cells 11, 12, 13 is rotated according to the rotational force of the precession motion by the atoms in each cell, and passes through the cells 11, 12, 13 to the detection unit 40. Incident.

  The detection unit 40 functions as detection means for detecting the probe light that has passed through the magnetic sensor array 10. As shown in FIG. 5 (b), the detection unit 40 includes detection units 41, 42, and 43. The detectors 41, 42, and 43 have photodetectors corresponding to the cells 11, 12, and 13, receive the probe light that has passed through the cells 11, 12, and 13, and analyze the electrical signal corresponding to the amount of light. Then, the rotation angle of the polarization plane of the probe light received in each cell is obtained, and magnetism corresponding to the rotation angle is detected.

(Operation)
Next, the operation in the case of measuring the magnetic field emitted from the specimen using the magnetic measurement apparatus 1 will be described. When magnetism measurement is started in the magnetic measuring device 1, pump light having a circularly polarized component is irradiated to each of the cells 11 to 13 of the magnetic sensor array 10 from each of the pump light irradiation units 21 to 23. . Thereby, the atoms in the cells 11 to 13 are excited by the pump light and spin-polarized in the same direction, and perform precession by changing the direction of the magnetic moment according to the magnetic field from the specimen. At this time, for example, some of the atoms in the cell 11 move to the cell 12 through the connection tube b11. However, since the connection tube b12 is provided at a position that is not an extension of the movement direction, the connection tube b12 is provided. Moving directly to the cell 13 through is restricted. As a result, the movement of atoms in each cell to non-adjacent cells is suppressed. Moreover, since each cell is connected by the connecting pipes b11 and b12 which connect the hole a provided in each cell, the gas pressure in each cell is uniform.

  Subsequently, each of the probe light irradiation units 31 to 33 of the probe light irradiation unit 30 is irradiated with probe light having a linearly polarized component to each of the cells 11 to 13 so as to be orthogonal to the pump light. The probe light incident on each of the cells 11 to 13 is transmitted through each cell with its polarization plane rotated according to the magnitude of the magnetic field received by the atoms in each cell. The probe light transmitted through the cells 11 to 13 enters each of the detection units 41 to 43 corresponding to each cell, and the probe light is received by the detection units 41 to 43. And in the detection parts 41-43, the electrical signal according to the light quantity of probe light is analyzed, the rotation angle of the polarization plane of probe light is calculated | required, and the magnetism in cell 11, 12, 13 is detected.

  Thus, since the magnetic sensor array 10 according to the above embodiment is configured by connecting the holes a provided in each cell with the connection pipe b, the gas pressure in each cell can be made constant. Further, in the magnetic sensor array 10, each cell is connected to the connecting pipes b11 and b12 so that the extension line in the moving direction of the atoms entering and leaving the connecting pipe b11 does not coincide with the extending line in the moving direction of the atoms entering and leaving the connecting pipe b12. Therefore, the gas pressure in each cell becomes uniform, and the magnetic measurement sensitivity in each cell can be made constant. Moreover, the movement of atoms to cells that are not adjacent to each other can be suppressed to a minimum, and the magnetic measurement accuracy in each cell is improved.

<Modification>
The present invention is not limited to the above-described embodiment, and may be carried out by being modified as follows. Further, the following modifications may be combined.
(1) In the above-described embodiment, the connection pipe b that connects each cell of the magnetic sensor array 10 is provided perpendicular to the adjacent surface, but is inclined by a certain angle with respect to the adjacent surface. The connecting pipe b may be provided as described above. Such an example is shown in FIG. FIG. 6 is a schematic diagram showing a magnetic sensor array 10 according to this modification. In this figure, the hole a11 of the cell 11 is provided at a higher position on the upper surface side than the hole a21 of the cell 12, and the hole a22 of the cell 12 is provided at a higher position on the upper surface side than the hole a31 of the cell 13. The connecting pipes b11 and b12 connecting these holes a are inclined with respect to the surfaces connected in the cells 11, 12, and 13. In the cell 12, by configuring the holes a21 and a22 as far apart as possible, the movement of atoms to cells that are not adjacent to each other can be further suppressed.

(2) In the above-described embodiment, an example in which the connection pipe b has a linear shape extending linearly in the pipe axis direction has been described. However, the connection pipe b may have a curved portion. , May have a bent portion. Such an example is shown in FIG. FIG. 7 is a schematic diagram showing a magnetic sensor array 10 according to this modification. FIG. 7A shows an example in which the cells are connected by connecting pipes b21 and b22 having curved lines in place of the connecting pipes b11 and b12 of the first modification described above.
FIG. 7B shows an example in which each cell is connected by connecting pipes b31 and b32 having a bent pipe shape instead of the connecting pipes b11 and b12 of the first modification described above. Thus, by making the connecting tube b into a curved shape or a bent shape, the movement of atoms can be suppressed as compared with the connecting tube having a linear shape.

(3) In the above-described embodiment, in the magnetic sensor array 10, each cell is arranged at a position separated by the length of the connection pipe b. May be configured to be connected to adjacent cells, and the connecting portion may function as the connecting pipe b. Such an example is shown in FIG. FIG. 8 is a schematic diagram showing a magnetic sensor array 10 according to this modification. In the example of FIG. 8, openings a11 and a21 are provided in a part of the upper part of the adjacent surface of the cell 11 and the cell 12, and openings a22 and a31 are provided in a part of the lower part of the adjacent surface of the cell 12 and the cell 13. The openings a11 and a21 are connected by a connecting pipe b41, and the openings a22 and a31 are connected by a connecting pipe b42. Thereby, a part of the upper surface of the cell 11 and the cell 12 is connected, and the magnetic sensor array 10 in which a part of the lower surface of the cell 12 and the cell 13 is connected is formed. Also in this case, as in the embodiment, since the extension line in the movement direction of the atoms entering / exiting the connecting tube b41 does not coincide with the extension line in the movement direction of the atoms entering / leaving b42, for example, the cell 11 The atoms inside cannot easily move to the cell 13, and the movement of atoms to a cell not adjacent to the cell 13 can be suppressed. In addition, since some of the cells are connected to adjacent cells, the cells can be arranged with high density.

(4) In the above-described embodiment, each cell is connected by the connection pipe b. However, for example, as shown in FIG. 9, the magnetic sensor array 100 may be configured without using the connection pipe b. . In the example of FIG. 9, for example, a wall that partitions the cell 101 and the cell 102 is provided with a common hole a <b> 1, and a wall that partitions the cell 101 and the cell 103 is provided with a common hole a <b> 2. . In addition, a common hole a3 is provided in the wall that partitions the cell 102 and the cell 104, and at least two common holes a are provided in the wall that partitions the other cells in the same manner. . Thus, in all the cells, by providing the hole a between the adjacent cells, the gas pressure in each cell can be made constant. In addition, as shown in FIG. 9, the common hole in each cell is provided so that the moving direction in which the atom moves in one hole in the cell does not coincide with the moving direction in which the atom moves in the other hole. Yes.

  That is, for example, with respect to the position of the hole a1 of the cell 101, the hole a3 of the cell 102 is provided in the downward direction of the wall opposite to the wall provided with the hole a1, and atoms move in and out of the hole a1. The extension line in the direction does not match the extension line in the movement direction of the atoms entering and leaving the hole a3. Therefore, even if atoms in the cell 101 pass through the hole a1 and move to the cell 102, the moved atoms cannot move to the cell 104 along the moving direction. Cannot move easily. The same applies to other cells.

In addition, when irradiating each cell of the magnetic sensor array 100 with pump light and probe light, the pump light irradiation unit is configured to irradiate the pump light from the lower surface of the magnetic sensor array 100 in units of cells in the arrow X direction. And a probe light irradiating unit is provided so as to irradiate the probe light in the direction of the arrow Y with respect to the cell groups in the respective columns A1, A2 and A3.
And it has a pump light irradiation control part which controls each pump light irradiation part so that pump light may be irradiated for every cell corresponding to a measurement object field, and probe light is applied to the row of cells irradiated with pump light. It comprises so that the probe light irradiation control part which controls the probe light irradiation part to irradiate may be provided. The atoms in the cell irradiated with the pump light are precessed by being excited by the pump light, so that the magnetism in each cell can be detected by detecting the probe light transmitted through the cell. In addition, when performing magnetic detection in each cell, by controlling the pump light irradiation unit and the probe light control unit so as to irradiate the pump light and the probe light by selecting the cells so that adjacent cells do not continue, Magnetism can be measured without being affected by atoms in a cell adjacent to the measurement target cell.

  DESCRIPTION OF SYMBOLS 1 ... Magnetic measuring device 10, 100 ... Magnetic sensor array, 11, 12, 13 ... Cell, 20 ... Pump light irradiation unit, 21, 22, 23 ... Pump light irradiation part, 30 ... Probe light irradiation unit, 31, 32, 33 ... Probe light irradiation unit, 40 ... Detection unit, 41, 42, 43 ... Detection unit

Claims (3)

A cell array having a plurality of cells containing therein an atomic group consisting of a plurality of atoms excited by circularly polarized light;
A pump light irradiation unit that irradiates each cell with pump light having a circularly polarized light component;
A probe light irradiation unit that irradiates each cell with a probe light having a linearly polarized component so as to be orthogonal to the irradiation direction of the pump light;
A detection unit for detecting the probe light irradiated to each cell by the probe light irradiation unit,
The plurality of cells are separated from adjacent cells by walls,
The wall is provided with holes,
A cell connected to two or more adjacent cells among the cells is connected to an extension line in the moving direction of the atom entering and exiting the hole communicating with one adjacent cell and to another adjacent cell. The magnetic measurement apparatus according to claim 1, wherein the hole is provided so that an extension line in a moving direction of the atom entering and exiting the hole does not coincide with the hole. The magnetic measurement apparatus according to claim 1, wherein the atomic group composed of the plurality of atoms is an alkali metal atom. The magnetic measurement apparatus according to claim 2, wherein a buffer gas is contained inside the cell.

Images